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Posted to notifications@couchdb.apache.org by nickva <gi...@git.apache.org> on 2017/01/27 21:54:09 UTC
[GitHub] couchdb-couch pull request #223: Remove 8kB read-ahead from couch_file
GitHub user nickva opened a pull request:
https://github.com/apache/couchdb-couch/pull/223
Remove 8kB read-ahead from couch_file
In production it showed an increased input Erlang IO and increased binary
memory usage.
See attached file in Jira ticket:
COUCHDB-3284
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/cloudant/couchdb-couch couchdb-3284
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/couchdb-couch/pull/223.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #223
----
commit d52a5335d930d11ade4953c8576d22f55872ff6f
Author: Nick Vatamaniuc <va...@apache.org>
Date: 2017-01-27T17:04:01Z
Remove 8kB read-ahead from couch_file
In production it showed an increased input Erlang IO and increased binary
memory usage.
See attached file in Jira ticket:
COUCHDB-3284
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[GitHub] couchdb-couch issue #223: Remove 8kB read-ahead from couch_file
Posted by rnewson <gi...@git.apache.org>.
Github user rnewson commented on the issue:
https://github.com/apache/couchdb-couch/pull/223
for clarity, we strongly believe the readahead to be a significant performance _regression_. It's not an improvement in any scenario we can see.
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[GitHub] couchdb-couch issue #223: Remove 8kB read-ahead from couch_file
Posted by nickva <gi...@git.apache.org>.
Github user nickva commented on the issue:
https://github.com/apache/couchdb-couch/pull/223
Out of curiosity create a branch which allows configuring file:open's read_ahead parameter:
https://github.com/cloudant/couchdb-couch/commit/3e35ae40f71fa84a3453b178caf774147300e87d
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[GitHub] couchdb-couch issue #223: Remove 8kB read-ahead from couch_file
Posted by kxepal <gi...@git.apache.org>.
Github user kxepal commented on the issue:
https://github.com/apache/couchdb-couch/pull/223
@nickva
You're going to revert [this optimization](https://github.com/apache/couchdb-couch/commit/c7b30071ac1a4166d44fc10f760a1a8ae2a8ae5c). Won't this impact on something else?
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[GitHub] couchdb-couch issue #223: Remove 8kB read-ahead from couch_file
Posted by kxepal <gi...@git.apache.org>.
Github user kxepal commented on the issue:
https://github.com/apache/couchdb-couch/pull/223
Hm...just checked your graphs in JIRA. They looks very nice.
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[GitHub] couchdb-couch issue #223: Remove 8kB read-ahead from couch_file
Posted by rnewson <gi...@git.apache.org>.
Github user rnewson commented on the issue:
https://github.com/apache/couchdb-couch/pull/223
+1
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[GitHub] couchdb-couch issue #223: Remove 8kB read-ahead from couch_file
Posted by davisp <gi...@git.apache.org>.
Github user davisp commented on the issue:
https://github.com/apache/couchdb-couch/pull/223
Awesome find. I've definitely been perplexed by the I/O changes since starting to deploy Couch 2.0 code. This definitely seems to explain both the io differences and the increase in memory usage.
The original commit even calls this a micro optimization so I'm inclined to completely remove it rather than make it optional. @kxepal, are you wanting to see a config option or are the graphs on the ticket convincing enough to just drop it?
Huge +1 from me.
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[GitHub] couchdb-couch issue #223: Remove 8kB read-ahead from couch_file
Posted by kxepal <gi...@git.apache.org>.
Github user kxepal commented on the issue:
https://github.com/apache/couchdb-couch/pull/223
@davisp
No, I'm waiting to have this merged (:
I wrote first post without knowledge about graphs, which are impressive - that's why reverting optimization for another optimization I found a bit strange.
+1 - that's what I forgot to add.
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[GitHub] couchdb-couch pull request #223: Remove 8kB read-ahead from couch_file
Posted by asfgit <gi...@git.apache.org>.
Github user asfgit closed the pull request at:
https://github.com/apache/couchdb-couch/pull/223
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